Kneaded products, such as a bread dough, a noodle dough such as wheat and buckwheat noodle, a confectionary dough, and a rice cake, are made by the steps of mixing, kneading and pounding predetermined ingredients into cakes.
In the case of making a bread dough with a direct kneading process, the steps described above contain repeated operations of first mixing ingredients such as flour, water, yeast, sugar, salt and shortening, and thereafter kneading and folding the obtained mixed ingredient. By appropriately and adequately carrying out these steps, hydration, that is, formation and binding of gluten, is promoted.
However, it takes considerable effort and is actually difficult to perform hand-kneading in these steps, that is, to perform these steps with hands. Therefore, in recent years, in not only households but also bread plants for mass-producing, these steps are carried out using a kneader utilizing not a human hand but a electric and mechanical power.
A kneader is a device for producing kneaded products, and has a kneading element disposed rotatably within a pot of the kneader. The kneading element is rotated by drive means about rotating shaft extending in an orthogonal direction of a bottom surface of the pot, whereby ingredients thrown into the pot can be mixed and kneaded.
Such kneaders or kneading elements used in the kneaders have been proposed in the past.
For example, an inventor of the present application has proposed a kneading element that is capable of promoting gluten binding in a kneading step by repeating the action similar to the “kneading” performed in hand-kneading (see Patent Literatures 1 and 2, for example).
The kneading elements of the kneaders described in Patent Literatures 1 and 2 each have a disk having a diameter slightly smaller than that of the bottom surface within the pot. A predetermined position on this disk is provided with parabolically radiating projected parts that extend from a predetermined height at a central part of the disk to a circumferential edge of the disk. The rear end face of each projected part in the rotating direction forms a bluffy erection surface. The section in front of the erection surface in the rotation direction in the kneading element forms a parabolic surface or a circular surface having an angle of 90° or lower with respect to the erection surface, in order to enhance the pressure-contact effect by mutually acting with the projected parts provided on the inner circumferential surface of the pot.
However, the kneading elements of the kneaders described in Patent Literatures 1 and 2 each are constituted by a discoid base having a diameter slightly smaller than that of the bottom surface inside the pot. For this reason, the problem is that ingredients and dough enter the space between the kneading element and the bottom surface within the pot and that these dough and the like cannot be removed.
Furthermore, the dough is rolled by centrifugal force generated by the rotation of the disk, and rolling friction, which increases as the hydration of the dough develops. Therefore, when the rolling friction surpasses the centrifugal force, the dough adheres to the disk and rotates integrally with the disk, and as a result, good kneading cannot be performed. Hence, another problem is that, when using this kneader, the diameter of the dough mass has to be equal to or less than the radius of the disk of the kneading element.
The inventor of the present application, therefore, has proposed a small and light kneading element that is capable of preventing the entry of a dough or the like into a space between a bottom surface within a pot and the kneading element as much as possible, and to immediately remove the dough even when the dough enters into the space (see Patent Literature 3, for example). In this kneading element, the diameter of the dough mass can be set at the length greater than the length of the blade of the kneading element or the radius of the bottom surface within the pot.
FIG. 20 is a diagram showing an embodiment of the kneading element described in Patent Literature 3, wherein (a) is a plan view and (b) a cross-sectional diagram taken along a line A-A in (a).
The kneading element described in Patent Literature 3 has a shaft center of the rotating shaft, and a pair of long and short semi-elliptical blades, one of the blades being longer than the other, with the line passing through the rotating shaft in a diameter direction between the blades. These blades are formed by bringing straight lines thereof into contact with each other, and one side of each blade from the shaft center of the rotating shaft (the front side in the rotation direction) is shorter than the other side (the rear side in the rotation direction). One side of one of the blades is the same length as the other side of the other blade, and circumferential edges of bottom parts of the blades are connected by the same arc. Moreover, as shown in FIG. 20(b), on each of the blades, a side surface part extending from the circumferential edge of the bottom part to the top surface of the blade forms a parabolic inclined surface that becomes steep gradually from the abovementioned one side to the other, and a deep bluffy erection surface is formed on a rotation direction back face (rear end part) of the other side of the abovementioned one of the blades. In addition, one side end of the abovementioned other blade is connected to a bottom part of the erection surface of the abovementioned one of the blades, and a shallow bluffy erection surface is formed on the rotation direction back surface (rear end part) of the other side.
According to this kneading element, the inclined surface of one of the blades mixes and kneads ingredients or a dough mass by moving and lifting up the ingredients or dough mass dropping the ingredients or dough mass in a deep bluffy erection surface area. Moreover, in this kneading element, even when the dough enters and adheres to the space between the element and the bottom surface within the pot, the entering dough is scraped out in a pot inner circumferential surface direction by the circumferential edge of the bottom part extending from one side of the blades to the other side of the blades. The remaining entering dough that was not scraped out is removed immediately by bonding with the dough mass that falls off the erection surface of the abovementioned one of the blades, as the kneading element rotates.
In a back surface area (rear side area) of the bluffy erection surface of the kneading element, because a layer of decompressed air is generated between the dough mass and the kneading element when kneading is performed, a force for rotating the dough more powerfully acts in the back surface area due to the decompressed air, and at the same time an action for preventing the dough from adhering to the bottom surface of the pot or kneading element is generated. Thus, even when kneading a large dough mass having a diameter equal to or greater than a radius of the bottom part of the pot, the dough is prevented from adhering to the kneading element, and therefore the dough does not rotate integrally with the kneading element. As a result, a phenomenon where kneading is not performed can be prevented.
However, as with the kneading elements described in Patent Literatures 1 and 2, in the kneading element described in Patent Literature 3 the pressure-contact effect from side surfaces of the projected parts provided on the inner circumferential surface of the pot is anticipated. In other words, in any of the kneading elements described in Patent Literatures 1 to 3, as shown in FIG. 20  (b), the shape of a side surface of the kneading element forms a parabolic or circular steep slope, the front side of which from the bluffy erection surface in the rotation direction drops drastically. Therefore, in the kneading element, the dough mass is pressurized by the steep slope in a direction of the projected parts, that is, in a direction substantially orthogonal to the bluffy erection surface.
When the dough mass is pressurized by the kneading element in an area without the projected parts, the pressure that the dough mass receives from the inner circumferential surface of the pot is not very large. Moreover, the presence of the projected parts in the inner circumferential surface of the pot makes it difficult to clean the inside of the pot after using the kneader.
For this reason, if possible, it is desired that the projected parts of the inner circumferential surface of the pot be eliminated so that the dough mass pressurized by the kneading element can receive great pressure directly from the inner circumferential surface of the pot in the entire area of the inner circumferential surface of the pot. In other words, it is desired that the kneading element be so shaped that the dough mass is pressurized directly toward the inside surface of the pot.
Note that another kneading element that reduces the adhesion of a dough to the kneading element and performs kneading by continuously compressing the dough is proposed (see Patent Literature 4, for example).
The kneading element described in Patent Literature 4 is formed such that when a side surface thereof is taken as a cross section in a surface including a rotation central shaft, the distance between one point on the side surface and the rotation central shaft decreases from a bottom part to the top surface or is constant. Further, this kneading element is formed such that when the side surface thereof is taken as a cross section in a surface orthogonal to the rotation central shaft, the distance between one point on the side surface and the rotation central shaft always increases in one rotation.
However, in the kneading element described in Patent Literature 4, because the side surface extending from the bottom part to the top surface is formed into a bluffy surface throughout the entire circumference of the bottom part, the kneading effect of scooping up a dough material is not very significant.
In addition, in the ideal kneading to be performed as soon as a dough mass is obtained, it is preferred that a circumferential edge part of the kneading element be embedded into a bottom part of the dough mass in a wedge shape, and that the dough mass be then placed on the side surface of the kneading element, moved while rotating the dough mass and then dropped into the area of a bluffy erection surface in a rotation direction rear end part of the kneading element. This is because the “kneading” and “folding” effect of so-called “hand-kneading” performed on the dough mass can be improved by this series of flows. However, in the kneading element described in Patent Literature 4, because the side surface extending from the bottom part to the top surface is formed into a bluffy surface throughout the entire circumference of the bottom part, this “hand-kneading” effect obtained in the series of flows described above is not very significant.
[Patent Literature 1] Japanese Unexamined Patent Application Publication No. S62-126928
[Patent Literature 2] Japanese Examined Patent Application Publication No. H5-78375
[Patent Literature 3] Japanese Examined Utility Model Application Publication No. H5-38828
[Patent Literature 4] International Publication WO2003/073860